HVAC controls retrofit and system troubleshooting

With Pentillion Construction, I helped audit, explain, and coordinate upgrades to an older HVAC control system. The building had existing controls and hardware that could not simply be replaced all at once, so the project needed a clear understanding of what was already there before the new work could be planned.

Understanding the old system before replacing parts of it

My role was to bridge the gap between the existing controls, the HVAC contractor, the controls contractor, and the practical needs of the building. I reviewed and documented how the system operated, helped explain the existing logic, and supported the retrofit so new equipment could be integrated without losing compatibility with parts of the older setup.

The upgrade included four new heat pumps. Because I had built much of the internal understanding of the existing controls, I became a practical reference point during the work. The value knowing what equipment was present and helping the contractors understand how the old controls, operating logic, and building requirements fit together.

Troubleshooting the shaking air handlers

That same system knowledge carried into troubleshooting. The building had two large air handlers that were shaking under certain operating conditions, and the cause had not been identified.

One proposed path was to bring in an engineering audit to measure resonant frequencies using specialized equipment. That may have been needed eventually, but before jumping to that step, I worked through a more direct inspection of the system.

Looking for the real field condition

I checked likely mechanical causes, including whether the air-handler shafts appeared to be off balance, the dampening system, and used a 360 camera and thermal imaging camera to inspect areas that were difficult to access directly.

That investigation pointed toward a loose sheet-metal wall dividing the large duct that supplied hot and cold air to the building. Under certain airflow and pressure conditions, the loose partition deflected until it relieved the pressure differential, then snapped back, allowing the pressure to rebuild and repeat the cycle. This created a low-frequency pulsation that transmitted vibration into the air-handler area and surrounding building structure.

A logical conclusion

I documented the old controls, identified what still had to work, coordinated the contractors around the real operating logic, and investigated the field condition before assuming the next step had to be expensive or abstract.

The result was a building system that became easier to explain, upgrade, maintain, and hand off.